An ambulance was called to a 45-year-old man. According to his family, the onset of the disease was sudden, after he returned from a ski resort. His body temperature increased up to 38.7 °C, he developed headache and vomiting. Objectively, his skin is pale with a cyanotic tint, there is a thick hemorrhagic rash all over the body, sometimes with necrosis in the center. Blood pressure is 45/0 mm Hg, pulse is 126/min., low volume. The patient has marked nuchal rigidity and positive Kernig’s sign. Make the provisional diagnosis: